Mrs. E5 th Grade Force and Motion

Force – push or pull a force always acts in a certain direction ex. if you push something, the force is in the direction of the push It can make things move faster, slower, stop, or change directions.

Forces on an Object Magnetism Gravity Friction

Magnets magnetism – force of attraction or repulsion A force that acts at a distance and cannot be seen. not all objects are affected by the force of magnetism ex. wood, glass, paper, plastic common metals affected by magnetism are iron, nickel, and cobalt

Compass the needle of a compass points toward the north pole or magnetic north because of the Earth’s magnetism. the Earth is a huge magnet so it has a strong magnetic force

Magnets poles – two ends of a magnet every magnet has two poles north (N) pole south (S) pole even if you break a magnet in half, each half will have a north pole and a south pole

Properties of Magnets if the north pole of one magnet is brought near the north pole of another magnet, they will repel each other, or push away if two south poles are brought together, they will repel each other, or push away

Properties of Magnets if a north pole and a south pole are brought together, they will attract each other opposites attract

Magnetic Fields magnetic field – area around a magnet where magnetic forces can act a magnetic field is made up of magnetic lines of force closer = stronger magnetic force farther = weaker magnetic force

Magnetic Fields magnetic lines of force – lines that show the shape of a magnetic field the magnetic lines of force are closest together at the poles of the magnet this is where the magnet is strongest

What is gravity? Sir Isaac Newton Hit on the head with an apple force of attraction between all objects in the universe the larger an object’s mass, the greater the gravitational force

Gravity the greater the distance between two objects, the smaller the gravitational force The less the distance between two objects, the greater the gravitational force.

What is friction? Friction force that opposes the motion of an object the force of friction works in the opposite direction of the force of motion You can see the effects of friction by watching something try to slide across a surface.

Friction friction makes motion possible friction also makes it hard to move objects along a surface Rougher the surface the more friction Smoother the surface the less friction reducing friction makes it easier to move objects along a surface

How can friction be reduced? by using lubricants Lubricants – substances that reduce friction Ex. Motor oil, wax, grease by making surfaces smoother Sanding, filing, smoothing by using rollers Wheels, hand truck

More Friction Friction occurs in liquids and gasses as well as solids.

Without Friction It would be hard to slow or stop the motion